To reduce projector size, there have recently been proposed light emitting devices in which a light source, such as an LED (light emitting diode), and a phosphor are used. For example, there is proposed a so-called reflective luminescent wheel in which light from a light source is converted in wavelength to fluorescence by a phosphor layer and the resultant fluorescence is reflected, by a reflective layer provided adjacent to a wavelength conversion member, toward the side through which the light from the light source has entered the phosphor layer, thus extracting the reflected light to the outside (see, for example, Patent Literature 1). The reflective luminescent wheel has the advantage of having a high efficiency of fluorescence extraction to the outside and therefore easily giving a high intensity to a projector.
Patent Literature 1 discloses, as the reflective layer, a metal layer made of gold, silver, copper, aluminum or others. Because the metal layer also has a high thermal conductivity and, therefore, can efficiently release heat generated in the phosphor layer to the outside, it has the advantage of effectively reducing temperature quenching of the phosphor (the phenomenon that the luminescence intensity decreases with increasing temperature of the phosphor).